1/2 Shank, 1/2 Arbor Dia., 1" Long. * For holding saws or small cutters. * Designed to fit directly into standard end mill adapters. *Made of alloy forged steel for long, durable service life. * Hardened to RC 56-60 and ground to ensure maximum accuracy. * Face is held perpendicular to center line within 0.0004". * Pilot diameter is sized for precision fit with cutter and is keyed for positive drive. * Heavy duty locking LH nut and three arbor spacers are included.